Those are 'Early girl hybrid' tomato from stem cutting. The seed package says 52 days maturity time. Also left over seeds from last year season. Acctually this is good variety for zone 3 because of the early maturity time, but I have grown this on my aerogarden, so it make me easy to make more plant, just take stem cutting from extra branch between the leaf ( sucker ). This extra branch is acctually mature plant, so it will grow as mature plant and hopefully get fruit early. I have tried this methode before on 2009 garden season , and I got fruit earlier . This is so easy methode and just basic skill needed.
First, sterilize knife with hydrogen peroxide, take stem cutting , you can take short cut or long cut , it doesn't matter how long the stem cutting is, because tomato plant is easy to root and grow fast too.
Second, rooting methode. You can choose two different methode. The most simple way is just leave the stem on the glass with about 1 inch of clean water, let it sit for couple days, change the water if necessary every day. After 4 or 5 days you will see root start forming on the stem. Then start repot the rooted stem to proper growing medium or potting mix.
Another methode is simple too , take stem cutting and apply rooting hormone, stick the stem on perlite or seed starting mix, then put on propagator . It will take same time about 4 or 5 days to form root on stem.
It is so instant, I think, because on a week you will have plant that look like 6 weeks old seedling. You can cut seed starting time and cost too by taking stem cutting. If you dont have ready plant at home, just start sow 1 seed of variety you want to grow very early, when the plant ready for haircut, then it is time to taking stem cutting. Another option is get ready plant in nursery, they will have tomato plant available around April, just get 1 plant per variety, then keep it indoor, then you can make more plant by taking stem cutting.